1. Field
Example embodiments of the present invention relate to bimetallic catalysts for a nitrate nitrogen reduction and manufacturing methods thereof. More particularly, example embodiments of the present invention relate to bimetallic catalysts including copper nanoparticles and palladium nanoparticles loaded on a hematite support, manufacturing methods thereof, and methods of decomposing nitrate nitrogen using the bimetallic catalysts.
2. Description of the Related Art
Nitrate nitrogen is widely known as a contaminant in industrial wastewater, livestock wastewater, underground water, etc. Having water contaminated by nitrate nitrogen can cause various health problems. Further, eutrophication may occur when nitrate nitrogen excessively exists in an ecosystem.
Methods of removing nitrate nitrogen include a biological denitrification, an ion-exchange method or a metal catalyst method. As for the biological denitrification, a treatment rate is very low, and a continuous carbon feed for microorganisms is needed. Further, a concentration of the microorganisms is not easily maintained in case of an environmental change, e.g., a change in a concentration of a treatment water, and a removal of the microorganisms and carbon is needed after treatment. As for the ion-exchange method, a salt water of a high concentration is used, and thus a treatment of concentrated salts is required. Further, a treatment water after treating a contaminated water may be corrosive.
Accordingly, methods of decomposing nitrate nitrogen using a metal or a bimetal loaded on a support have been researched. Particularly, various methods of efficiently decomposing nitrate nitrogen using the bimetal have been progressed. In the methods, metals including copper (Cu), tin (Sn), nickel (Ni), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), etc., have been loaded on various supports. Recently, a combination of copper and palladium has been known to efficiently decompose nitrate nitrogen by generating a nitrogen gas.
To reuse a catalyst for decomposing nitrate nitrogen, a suitable support has been developed. In a recent developed approach, a transition metal is loaded on a magnetic support to be used for a reduction reaction, and then the catalyst is recovered using a magnet.
For example, in Korean Patent Publication No. 10-2010-0108040 published on Oct. 6, 2010, a method of decomposing nitrate nitrogen using a catalyst in which a transition metal is loaded on zerovalent iron is disclosed. In Environ. Sci. Technol. 43 (2009) p 2482-2488, a catalyst is manufactured by loading copper and palladium precursors on iron particles. In Applied Catalysis B: Environmental 46(2): p 341-351, a catalyst is manufactured by loading copper and palladium on titania.
In Korean Patent Publication No. 10-2013-0113120 published on Oct. 15, 2013, lepidocrocite is used as a starting material, and a maghemite catalyst on which copper and palladium are loaded is manufactured.
Despite the above mentioned technologies, a development of a catalyst having a high efficiency of reductively decomposing nitrate nitrogen and a high selectivity for a non-toxic final product of nitrogen gas is still required.